I have been working on utilizing the SMUX and other sensors to help us create new autonomous programs. I have been working on the robot for the past week and have run into several problems most of which I think I have resolved. However before I continue, I'd like to piggyback off of the expert experience here so that I can save an hour or two.

However, we discovered that the Lego Color Sensors seem to not be supported by the SMUX. We also found that the gyro would return values of '0' 75% of the time on the SMUX. This lead us to getting rid of 1 color sensor and moving the gyro and the remaining color sensor to the NXT.

I have gotten the IR Sensors to return values, however, I have not implemented the values yet as the gyro and color were the first problems to deal with. So I don't know if the IR values will work as expected yet. I have not tried anything with the Lego Ultrasonic yet. (except setting it up with the SMUX)

Can someone please confirm the following? 1. The Lego Color Sensors are NOT supported by the SMUX 2. The Gyro Sensor is finicky when used on the SMUX (in conjunction with 3 more sensors on the SMUX) 3. The IR Sensors WORK on the SMUX 4. The Lego Ultrasonic will WORK on the SMUX.

Thank you!

_________________FTC 7104 - The Synergists

Thu Feb 19, 2015 2:31 pm

MHTS

Guru

Joined: Sun Nov 15, 2009 5:46 amPosts: 1523

Re: SMUX and IR/Lego Color/Lego Ultrasonic/Gyro

Synergists wrote:

Can someone please confirm the following? 1. The Lego Color Sensors are NOT supported by the SMUX 2. The Gyro Sensor is finicky when used on the SMUX (in conjunction with 3 more sensors on the SMUX) 3. The IR Sensors WORK on the SMUX 4. The Lego Ultrasonic will WORK on the SMUX.

Thank you!

1. We never tried using Lego color sensors on a SMUX, so can't confirm it either way.2. We had gyro on SMUX before and didn't have any problem. This year we have it on the NXT directly because the gyro is considered one of the "essential sesnors" on the robot. If for some reason the students forgot to turn the SMUX power ON, we want the essential sensors still working. So we put only non-essential sensors on the SMUX.3. We have 2 IR seekers on SMUX this year, so they are definitely working.4. We have 2 sonar sensors on SMUX this year too and have no problem with them.

The LEGO NXT Color Sensor does NOT work with the HT Sensor MUX. The LEGO NXT Color sensor is a strange animal. It is not I2C and not like a normal analogue sensor. LEGO, in their infinite wisdom, figured it would be much better to make up a new sensor system, that is only used for a single sensor and then not document any of it properly. Go figure. The HT Sensor MUX will work with most, if not all, proper analogue NXT sensors and I2C sensors that don't require writes to them to activate or initiate them.

There is currently no way to get the RGB data from the LEGO NXT Color sensor in one go, the functionality was not implemented. I tried to fabricate a work-around for you, but the firmware is not accepting the unimplemented mode. I had hoped to be able to use some low-level functionality to fetch the datasets through other means, alas, t'was not to be.

The LEGO Color Sensor is in fact MUCH faster than the HT one, but it can only detect about 6 colours. The HT one can detect 17 of them. Philo did a nice comparison on his page: http://www.philohome.com/colcomp/cc.htm

6 colors.. yes if the kids just uses the cooked data. I am showing them the knowledge of RGB (0xff, 0xff, 0xff), and gets as robust values as possible by analyzing the 255, 255, 255 ranges.

This is rather urgent just because they are going for the RCJ /USA in April. NXT kids will just have to put that RGB probing in the background for the time being... not ideal, but will have to do. Or, try the Hitechnic one.. just that they all have already had 2 nxt color sensors ...I am trying to help them saving money there.

The biggest issue is the green. The game rule does not provide a range of Green shade... just say green!!!! I can get a typical green tape from Lowes, and read black.. but with RGB, they can tell it is actually still green.

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